Stir plate magnet question (Pull strength)

[phoenixs4r]

I, like most, built my stir plate out of stuff laying around. This includes two magnets from an aquarium scrubber.

They are....ok... They aren't strong enough for my taste. For anyone who has purchased magnets, what pull rating do you use?

What pull strength?
What size starters?
How often does your magnet fly off?

I'm asking because I'm trying to only drink what I brew, and to cut costs, I want to create 4 starters off of 1 vial, and I'll be buying a bunch of magnets.

Cheers,

 

[sj_engr]

Used a magnet from a HDD. Seems to have some serious str.

 

[Catt22]

I've been using a pair of these on my stir plates.

http://www.rare-earth-magnets.com/p-65-nsn0582.aspx

They are rated at 16 lbs pull force each. They are scary strong. You can vary the pull exerted by changing the gap between the magnets and the flask. The most important thing is to have the magnets precisely spaced and aligned. This will ensure smooth, quiet operation with much less chance of throwing the bar. This is also easier said than done. Space the magnets to match whatever length of stir bar you are planning to use for optimum performance.

 

[ekjohns]

I went to joann's fabrics and bought 2 packets of these More than enough power to go from off to max speed without even a hint of the stir bar coming off. Hobby lobby also sells similar magnets

 

[RoadKing]

I looked over theese and then came up with a plan..http://stir-plate.com/Build.htm

 

[phoenixs4r]

I grabbed some 16 pounders. We'll see if this works better....

 

[Catt22]

I grabbed some 16 pounders. We'll see if this works better....

Good choice, but be sure you precisely space and align the magnets. Match the spacing with the stir bar you plan to use. I'm currently running a 2-1/2" bar with the same magnets with excellent results.

 

[brewguyver]

I grabbed some 16 pounders. We'll see if this works better....

bump

How did the 16 # magnets work? I'm looking at building a stir plate during new years week, and trying to figure out what I should use. I'm planning on using an old, ineffective humidor as the box, so there's probably 1/4" of wood between the stir bar and the magnets.